The present invention relates to electrical disconnects for mounting in cabinets and having a forwardly-extending, rotary shaft that may engage a handle on the cabinet door when the cabinet door is closed, and in particular to an improvement in such a disconnect that reduces the chance of current flowing through the disconnect when the cabinet door is open.
Referring to FIG. 1, a disconnect in the form of a standard fuse block 10 of the prior art may receive fuse cartridges 12 along its front face and may attach at its rear face to the rear wall 14 of a metal cabinet 16.
Input terminals along the top of fuse block 10 may receive wires 18 which connect independently to one side of each fuse cartridge 12, the latter which interconnect wires 18 to wires 20 attached to output terminals along the bottom of the fuse cartridge 12. Wires 18, for example, may be connected to a source of three-phase power and wires 20, for example, may be connected to a motor or other piece of equipment.
Fuse block 10 may be activated to electrically disconnect wires 18 from the respective fuse cartridges 12. The fuse block 10 may be controlled by a rotary shaft 22 along one side of the fuse block 10 and extending in an orientation perpendicular to the rear wall 14 of cabinet 16 toward an open face of the cabinet.
The open face of the cabinet may be covered by a door 24 attached by hinges to one side of the cabinet 16. Door 24 may support a captively mounted rotary knob 26 having an inwardly extending connector 28.
Referring now to FIG. 2, knob 26 may include connector 28 that extends inwardly through an opening in the door 24. Connector 28 includes retaining flanges 30 for retaining it rotatably within that opening.
When door 24 is closed about the cabinet 16, connector 28 of the knob 26 engages the outermost end of rotary shaft 22, thereby allowing rotary shaft 22 to be operated by knob 26 when door 24 is closed on cabinet 16. Specifically, an inwardly facing end of connector 28 may include a keyway 32 receiving a rectangular end of rotary shaft 22 and a pin 34 extending perpendicularly through the rotary operator. Turning knob 26, in turn, rotates shaft 22 to electrically disconnect or connect power to wires 20.
Referring again to FIG. 1, knob 26 allows disconnection of power to wires 20 when the door 24 on the cabinet 16 is closed. However, when door 24 is open, rotary shaft 22 is exposed, thereby enabling power to be inadvertently reconnected by counter rotation the shaft 22.
One apparatus for preventing the reconnection of power while the door is open includes bracketing that is connected to the exterior of fuse block 10. The bracketing enables knob rotation to connect and disconnect the power when the door is closed, and further prevents inadvertent counter rotation of the knob to reconnect the power when the door is open. While this apparatus is suitable for its intended purpose, the bracketing requires modification of an existing fuse block.
It would therefore be desirable to provide a less intrusive mechanism for preventing rotation of the operator in a direction that would reconnected power when the cabinet door is open.